The invention concerns a device for the application of fluid substances in printing and coating machines, and more particularly to such a device which includes carrying plates which are attached to a carrying beam and which include recesses therein within which pivot axles of a magnetic application roller are loosely rotatably disposed.
In known devices of this type, an application roller (or ductor roller) is caused to press against a fabric strip, which is to be imprinted, by a magnetic beam arranged below the fabric strip. The carrying plates of such a roller should prevent unintentional deviation of the roller from its desired direction and allow for removal of the roller from the carrying plates.
An important advantage obtained by magnetically causing a ductor roller to press against the fabric strip is that essentially no forces are introduced at the ends of the roller so that no deflection of the roller occurs. In order to assure this advantage, the carrying plates provided are not designed as bearings which fix the position of the pivot axles, but as a type of cage which limits the amount which the roller can deviate from its normal position in the horizontal plane and which allows the roller to be removed from the carrying plates. Because the roller, in this arrangement, is allowed to move somewhat in the horizontal plane, the roller may become slanted relative to its normal position transverse of the running direction of the fabric strip. Such slanting of the roller may cause operational problems. For example, slanting of the roller while it is rotating will cause it to shift in the axial direction and thus cause its pivot axles to bear against stopping surfaces provided on either side of the rollers to limit the crosswise movement of the roller. This leads to wear of both the stopping surfaces and the pivot axles.
In addition, in some prior art fluid substance applying machines such as those described above, and in particular in rotary screen printing machines, the carrying beam is used for supplying the fluid substance to the working area. Because the carrying beam usually has a relatively large diameter, upon changing color or performing maintenance work on the device, there is a considerable loss of the fluid substance.